1. Field of the Invention
The present invention generally relates to devices and processes for testing optical tape media and, more particularly, to a drum design that facilitates the mounting of optical tape media thereon and an apparatus and method for mounting optical tape media on a drum.
2. Relevant Background
Optical tape is a type of digital storage media that is generally in the form of a long and narrow strip of plastic that is designed to wind around a number of reels and be moved in first and second opposite longitudinal directions by a drive motor (the reels and drive motor being known as a “tape transport system”). As the optical tape is moved about the reels by the drive motor, digital content (e.g., binary data in the form of a series of encoding patterns) may be written and read by one or more lasers which may be embodied in one or more optical pickup units (OPUs).
The encoded binary data may be in the form of “marks” (e.g., indentations, indicia) and “spaces” (e.g., the portion of the tape between adjacent pits) disposed on one or more encoding or recording layers (e.g., each including a dye recording layer, a phase change material such as AgInSbTe, and/or a semi transparent metal reflecting layer). Generally, the smaller the indicia are on the optical media, the higher the capacity is of the optical media.
Testing and evaluation is a vital aspect of the development and production of optical tape media, especially as the size of the pits, lands and other indicia on the optical tape media decreases. Several methods can be used to assess the quality of optical tape media such as measuring its optical signals during a process of reading and/or retrieving data (e.g., sum signal, differential push pull tracking error signal, focus error signal), examining the integrity of its physical and logical formats, performing interchange testing, conducting data verification, and/or the like. For instance, optical signal data may be used to perform a jitter analysis and/or to measure thickness and/or roughness of the media to determine whether the various properties of the optical media are within established tolerances. Each method may be considered a piece of the quality testing puzzle.
In some arrangements, a fully developed tape transport system is used to move an entire length of optical tape media past one or more OPUs which may be used to obtain signals from the entire length of tape and pass such obtained signals to any appropriate arrangement of amplifiers, control units, and the like to test and evaluate various aspects of the optical tape media. In other arrangements, a short segment of a length of optical tape can be mounted on a testing drum which is spun by a motor to repeatedly pass (e.g., rotate) the segment past one or more OPUs for use in obtaining signals and data from the segment. Processing of the signals and data from the short segment can be used to provide an indication of various properties or qualities of the entire length of optical tape from which the segment was obtained.